Heating, ventilating and air conditioning (HVAC) systems, such as gas-fired HVAC systems, can generate condensate liquid (water) as a byproduct of the combustion process during heating operations. Typically, a condensate trap is included in the drain system of the HVAC system to prohibit flue gases from entering the drain system or the installed environment while allowing the condensate liquid to drain.
HVAC systems installed in an unconditioned environment can be subject to ambient temperature below freezing and therefore have the risk of the condensate liquid freezing within the condensate trap. Frozen condensate in the condensate trap can block the flow passageway of the condensate trap, which in turn, can prevent condensate being removed from the system. Under such conditions, further condensate liquid generated during the HVAC system's operation may back-up into in the drain system and other components of the system distill to the trap and potentially prevent the proper operation and/or cause damage to the system.
Often, to prevent condensate liquid from freezing in the condensate trap, electrical heating tape is applied to the condensate trap. Some disadvantages of using electric heat tape can include: the requirement for, and consumption of, electrical power to produce resistive heating by the electrical heating tape; the loss in ability to prevent condensate freezing if electrical power to the heating tape is lost; reliance on field personnel to properly install the heating tape; and the degradation and failure of the electrical heating tape over time. Similar limitation can exist for other heating devices that rely on heating generated via resistive heating (also referred to as Joule or Ohmic heating).
Therefore there is a need for a freeze tolerant condensate trap that does not suffer from the drawbacks of previous condensate traps or previous solutions to prevent condensate freezing in such traps.